ICU-23272 Fix long skeleton crash while parsing

Author: FrankYFTang

icu4c/source/i18n/unicode/numberformatter.h

@@ -1232,7 +1232,7 @@ class U_I18N_API StringProp : public UMemory {
     StringProp &operator=(StringProp &&src) noexcept;
 
     /** @internal */
-    int16_t length() const {
+    int32_t length() const {
         return fLength;
     }
 
@@ -1250,7 +1250,7 @@ class U_I18N_API StringProp : public UMemory {
 
   private:
     char *fValue;
-    int16_t fLength;
+    int32_t fLength;
     UErrorCode fError;
 
     StringProp() : fValue(nullptr), fLength(0), fError(U_ZERO_ERROR) {

icu4c/source/test/intltest/numbertest.h

@@ -305,6 +305,7 @@ class NumberSkeletonTest : public IntlTest {
     void perUnitInArabic();
     void perUnitToSkeleton();
     void measurementSystemOverride();
+    void longSkeletonCrash();
 
     void runIndexedTest(int32_t index, UBool exec, const char*& name, char* par = nullptr) override;
 

icu4c/source/test/intltest/numbertest_skeletons.cpp

@@ -35,6 +35,7 @@ void NumberSkeletonTest::runIndexedTest(int32_t index, UBool exec, const char*&
         TESTCASE_AUTO(perUnitInArabic);
         TESTCASE_AUTO(perUnitToSkeleton);
         TESTCASE_AUTO(measurementSystemOverride);
+        TESTCASE_AUTO(longSkeletonCrash);
     TESTCASE_AUTO_END;
 }
 
@@ -572,4 +573,12 @@ void NumberSkeletonTest::measurementSystemOverride() {
     }
 }
 
+void NumberSkeletonTest::longSkeletonCrash() {
+    IcuTestErrorCode status(*this, "longSkeletonCrash");
+    UErrorCode err = U_ZERO_ERROR;
+    UnicodeString skeleton(u"K\n%\nusage/");
+    skeleton.padTrailing(65535, 0);
+    UnlocalizedNumberFormatter nf = NumberFormatter::forSkeleton(skeleton, err);
+}
+
 #endif /* #if !UCONFIG_NO_FORMATTING */